Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int main(){
  int h, w, white = 0;  cin >> h >> w;
  char s[55][55];
  for(int i=1; i<=h; i++)
    for(int j=1; j<=w; j++){
      cin >> s[i][j];
      if(s[i][j] == '.')  white++;
    }
  
  int cost[55][55] = {0}, d[] = {1, 0, -1, 0, 1};
  cost[1][1] = 1;
  queue<pair<int, int>> que;
  que.push({1, 1});
  while(!que.empty()){
    int nowh = que.front().first, noww = que.front().second;
    que.pop();
    for(int i=0; i<4; i++){
      int nexh = nowh + d[i], nexw = noww + d[i+1];
      if(s[nexh][nexw]=='.' && !cost[nexh][nexw]){
	que.push({nexh, nexw});
	cost[nexh][nexw] = cost[nowh][noww] + 1;
      }
    }
  }

  int ans =  white - cost[h][w];
  if(!cost[h][w])  ans = -1;

  cout << ans << endl;

  return 0;
}